AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 3 672-R677, Copyright © 1990 by American Physiological Society
Pituitary-adrenal and adrenomedullary responses to noise in awake dogs
W. C. Engeland, P. Miller and D. S. Gann
Department of Surgery, Brown University, Rhode Island Hospital, Providence 02903.
Experiments characterized the dynamics of the pituitary and adrenocortical
response to noise in awake dogs to determine if a dissociation exists
between changes in plasma bioactive (bio) adrenocorticotropic hormone
(ACTH) and immunoreactive (ir) ACTH. In addition, experiments determined
the temporal relationship between cardiovascular, adrenomedullary, and
adrenocortical responses induced by the acute presentation of noise.
Trained dogs were prepared chronically with adrenal venous and femoral
arterial cannulas. Experiments were done 48-96 h postsurgery and consisted
of presentation of noise (75 dB; 0.25-8 kHz) for 3 min (n = 6) or of blood
sampling alone (n = 5). In response to noise, mean arterial pressure and
heart rate increased at 30 s and returned to base line at 4 min. Adrenal
secretion of epinephrine and norepinephrine increased at 1 min and remained
elevated until 4 min. Adrenal blood flow increased from 2 to 4 min as the
result of a parallel increase in adrenal vascular conductance. Plasma
bioACTH increased from 6 to 15 min in parallel with that of plasma irACTH.
Before noise, the ratio of bioACTH to irACTH was 0.2-0.3, but the absolute
change in bioACTH and irACTH after noise was not different. The increase in
plasma ACTH occurred concomitant with or preceded an increase in cortisol
secretion. Blood sampling alone caused no change in any variable. These
data show that unexpected noise evokes a sequence of responses with rapid
onset that includes tachycardia, hypertension, and increases in
adrenomedullary secretion and adrenal vascular conductance.(ABSTRACT
TRUNCATED AT 250 WORDS)
